It is known for a camera to be used with a film cassette having a light lock which is to be pivoted closed after a filmstrip exposed in the camera is completely wound into the cassette. The light lock must be pivoted closed to prevent ambient light from entering the film cassette when the cassette is removed from the camera. The camera includes a manual film winding thumbwheel which is windingly rotated with a first part of the thumbwheel coaxially engaging a film spool inside the film cassette, to progressively wind the exposed filmstrip onto the spool following each exposure. A second part of the thumbwheel, separate and distinct from the first part, operates a closing mechanism to pivot the light lock closed when the thumbwheel is continued to be windingly rotated after the exposed filmstrip is completely wound into the cassette following the last exposure. A version of the camera is disclosed in commonly assigned U.S. Pat. No. 5,608,480 issued Mar. 4, 1997.